The present invention relates to an elevator hoisting machine for an elevator mounted on and fastened to one side of an elevator or counterweight guide rail.
Prior-art technology in the field of the invention is described in patent specification EP 0688735 A2. This specification presents a flat overall solution for use in elevators, which is so mounted in the hoistway that no separate machine rooms are needed. A hoisting machine is mounted on a guide rail in the hoistway, either a car guide rail or a counterweight guide rail, either directly or using a suitable auxiliary frame. Such a hoisting machine allows an arrangement of the various elevator structures that is very advantageous in respect of space utilization as regards the building as a whole as well as the elevator itself.
Such a hoisting machine is relatively noiseless and free of vibrations when operated at low speeds. However, when the traveling speed is increased, sooner or later a speed range will be reached where, due to the cyclic nature of the field variations occurring in the electric motor, the excitation frequency generated by the motor is of the same order as the natural vibration frequency of the stator frame of the machine. Therefore, the forces acting between the rotor and the stator may cause vibrations in the stator frame that are sufficient to produce noises of a disturbing intensity in the hoistway, elevator car as well as outside the hoistway. In flat hoisting machines placed in the hoistway, the brakes, which are mounted on the sides of the machine frame, act as mass concentrations which, together with the frame, constitute in the hoisting machine a subsystem having relatively low natural vibration frequencies. When it is required that the elevator provide a high level of traveling comfort and produce a low level of airborne noise and a low oscillation level of structure-borne noise radiating from the elevator to the building, the question of controlling the lowest range of natural frequencies of the hoisting machine becomes very important because these are likely to determine the maximum disturbance-free velocity that can be used. Making the machine frame more rigid would easily lead to an undesirable increase in the weight and size of the machine.
Traditionally, the vibrations and noise produced by the elevator hoisting machine have been relatively easily eliminated to a sufficient degree by improving sound insulation in separate machine rooms and by mounting the machine on a bed provided with vibration insulation. However, when the hoisting machine is placed in the hoistway, there is no space around it that would allow the provision of any significant sound insulation or arrangements for damping sound propagation in the structures. Consequently, instead of noise abatement, the hoisting machine itself has to be structurally so designed that it will work quietly enough not to disturb passengers in the car or people in the vicinity of the hoistway in the building.
Thus, the object of the invention is to disclose a flat elevator hoisting machine, in other words, an elevator hoisting machine having a relatively short dimension in the direction of the axis of the traction sheave, a machine which has a low level of noise and vibration, i.e. a machine which, regardless of the car speed, produces as little vibration and noise effects in the hoistway, in the car and outside the hoistway as possible. A further object of the invention is to disclose a flat elevator hoisting machine which, in spite of vibration-free and noiseless operation, still requires but extremely little space in the hoistway and is therefore easy to install in the hoistway. Another object of the invention is to improve the hoisting machine concept known from specification EP 0688735 A2.
An elevator hoisting machine mounted on the side of an elevator guide rail or a counterweight guide rail makes it possible to build an elevator without a machine room that provides significant advantages regarding structural aspects and space utilization.
As the hoisting machine is fixed to the guide rail via the operating brakes or by a point in the immediate vicinity of the operating brakes, the guide rail functions as an additional reinforcement of the machine frame of the hoisting machine in a particularly favorable manner. The lowest natural vibrations of the machine are generated as the heavy brakes supported by the relatively wide machine frame are vibrating. The frequency of this vibration can be increased by stiffening the frame so as to provide more resistance to the vibration of the brakes. By making use of the elevator guide rail to obtain additional reinforcement, separate measures increasing the weight and/or thickness of the machine are avoided. Or if the level of vibration and noise is satisfactory, then the selective additional stiffness provided by the guide rail may even allow the use of a lighter hoisting machine frame.
Placing the brakes at the upper and lower edges of the machine provides the additional advantage that the hoisting machine is also narrow besides being flat, thus allowing the machine to be installed even in a very narrow hoistway, making it excellently applicable for use in repair and modernization construction projects.
Mounting the shaft of the traction sheave on the guide rail increases the stiffness of the structure or alternatively allows lighter suspension of the shaft on the frame of the hoisting machine.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.